Arrangement for regulating the height of the lubricating film on the slide tracks of machine tools



May l, 1962 H. AXER ETAL 3,032,142

AERANGEHENT EGE REGULATTNG THE HEIGHT 0E THE LUBRTCATTNG FILM oN THE SLIDE TRACKS oF MACHINE TooLs Filed Aug. 8, 1960 2 Sheets--Shee'rl 1 Il llIIII WVM/70,95

WF@ a@ May 1, 1962 H. AXER ETAL. 3,032,142

AFRANGEMENT FOR REGULATING THE HEIGHT 0F THE LUBRICATING FILM ON THE SLIDE TRACKS OF MACHINE TOOLS Filed Aug. 8, 1960 2 Sheets-Sheet 2 United States ARRANGEMENT FOR REGULAT ING THE HEfGHT OF THE LUBRCATNG FILM N THE SLIDE TRACKS OF MACHINE TOOLS Heinrich Axer, Neuss (Rhine), Wolfgang F. Hlken,

Ratingen, near Dusseldorf, and Otto W. Ufert, Dusseldorf-Oberkassel, Germany, assignors to Schiess Aktiengesellschaft, Dusseldorf-Gberkassel, Germany Filed Aug. 8, 1960, Ser. No. 43,313 4 Claims. (Cl. 18d- 5) This invention relates to an arrangement for lubricating the slide tracks of machine tools, and more particularly to an arrangement or system for regulating the height of the lubricating film or lubricating gap between the face plate and the support bed of a vertical lathe.

Machine tools such as milling or planing lathes, comprise heavy parts e.g, work piece holders, rotary tables, face plates etc., which move in special tracks or guide ways either in rotary or in reciprocating paths. These heavy moving parts require proper lubrication at all times, which must be satisfactory even as the amount of friction between the parts changes with the speed variationsof the movable part or with the load which is ap` 'plied to it.

Arrangements or systems in which a lubricant means such as oil is fed under pressure between a slide track and the body sliding thereon are already known. This pressure is such that the weight of the face plate as well as that of the work piece carried thereby is supported by the lubricant lm formed in this gap. The known arrangements and systems for regulating the height of the lubricating film do not provide a film which remains constant in height regardless of the weight and position of the load carried by the moving part and regardless of the speed or motion of the latter.

It is therefore an object of `the present invention to provide an arrangement or system for lubricating the guide track of machine tools in which the height of the lubricating film remains constant regardless of the weight and position of the load placed on the moving part and regardless of the speed or motion of the latter. p

It is another object of the invention to provide an arrangement or system for lubricating machine tools in which the regulation or control of the lubricating film is not influenced by particular characteristics of the machine or the lubricant.

It is a further object of the invention to provide an arrangement or system for lubricating machine tools in which an equalization between the desired value or height of the lubricating film and its actual value is possible.

Local variations in the height of the lubricating film can arise if the face plate is not mounted exactly parallel to the support bed or if the face plate is inclined due to an eccentric load.

It is therefore still another object of this invention to Vprovide a lubricating arrangement in which any dislocation or inclination of the face plate and corresponding change in the height of the lubricating film is picked up locally and is immediately corrected upon arising by an increase of the amount of lubricant supplied to that particular spot.

The above objects of the invention are accomplished by arranging spaced sensing means in the path of the guide track which constantly sense the actual value of the lubricant film height and by feeding the impulses thus derived to associated means which compare the desired value or height of the lubricating lm with the actual value, from where any differences which may be derived are employed, after suitable amplification, to vary the lubricant supply to the lubricant gap through control devices which operate independently of each other.

3,032,142 Patented May 1, 1962 In machine tools which have a slide track provided with depressions in which a lubricant under pressure forms a pressure cushion, sensing means or feelers can be arranged in the depressions along the length or circumference of the guide track. Each sensing means is coupled with a device for comparing the desired film height with the actual film height. rlhe comparison device in turn is coupled through an amplifier with a control motor which regulates control means for adjusting the amount of lubricant fed to the respective depressions in the slide track.

The amount of lubricant supplied to the depressions in the slide track can be regulated by a throttle valve which is controlled by the impulses derived from the sensing means provided in the depressions. According to one embodiment of the invention a control motor, the speed of which is responsive to the impulses derived from the sensing means drives one sun gear of a bevel gear drive, while a constant speed motor drives the other sun gear of the bevel gear. The rotation of the connecting shaft of the planetary gears operates the throttle valve which is provided in the supply line of the pressurized lubricant between a pump and the depressions in the slide track.

The connecting shaft of the planetary gears may be connected through a spindle drive to the regulating means for the lubricant supply.

The invention is disclosed by way of an embodiment which is described hereafter and is shown in the accompanying drawings which form a part hereof, in which:

FIG. l is a schematic diagram of the lubricant control arrangement of this invention with a partial section of a circular slide track showing a depression in the support bed and the lubricant supply line thereto.

FIG. 2 is a schematic diagram showing in elevation the lubricant supply arrangement of a circular face plate with the lubricant control devices of FIG. l.

The circular face plate 1 of a vertical lathe is mounted on a support bed 2. The track or guide surface 3 is provided with a concentric lubricant supply canal which is subdivided by web portions 4 into individual pressure chambers 5 (FIG, 2). The number of these pressure chambers 5 may vary depending on the size of the face plate such that it would increase for example with an increase of the diameter of the face plate. The supply of lubricant to the chambers 5 is of sufficient pressure to create a gap 6 the height a of which is to remain constant regardless of the weight of the load to be carried by the face plate or the speed of rotation of the face plate and regardless of whether the load is placed on one particular portion of the face plate or is distributed uniformly.

The actual value or height of the lubricating gap 6 is measured constantly by a sensing means or feeler 7 which may be arranged appropriately in the center of each pressure chamber 5 and which may have either an inductive. or a capacitive or an hydraulic collecting or controlling means. The measured value is transmitted as impulse through a line 7 to a device which compares the desired value or height of the lubricant to the actual value, for example to a control compensator 8, which is impressed with or adjusted to the desired value. From this compensator any difference between the desired value and the actual value is transmitted through a line 8' to an amplifier 9. for example an electronic amplifier, and from this amplifier through a line 9 to a control motor 10 (FIG. l).

The lubricant is fed through a common supply pipe l2 under a predetermined constant pressure by means of a gear pump 11 to the pressure chambers 5 of the guide track. The gear pump 11 is driven at a constant speed by vof the lubricant gap a.

an electric motor V11". T he different control devices which are employed with the same machine are connected to pipe 12, which consists of a circular conduit in the case of a rotary machine as shown in FIG. 2. The pressure of -pump 11 is controlled by means of an overow valve 13 Awhich is of conventional construction and is therefore not specifically described nor shown in detail in the drawing from where the lubricant discharged by the overow valve is returned to the lubricant supply vessel 11' of pump 11. In the embodiment shown a single pump is used for the control devices, although each control Vdevice could be provided with a separate pump. In the case of a common supply pipe 12 and a single pump 11 the individual control devices 23 are connected through branch condui-ts 12' with the individual pressure chambers of the guide track and through branch conduits 12 to the circular supply pipe 12.

Besides the overflow valve 13 a second flow control means, for example a throttle valve 14, is provided in the supply line between theY pump and the pressure chambers. Throttle valve 14 which is of conventional construction and is therefore not specially described nor shown in detail in the drawing has a slidable piston 15 which operates to change the amount of lubricant supplied to the respective pressure chambers and thus regulates the height Piston 15 is actuated by means of a piston .rod divided into two sections the length of which may be altered through a helically threaded spindle drive 24. Piston rod section 17 is connected to the valve piston and carries the fem-ale part 16 of the helically threaded spindle drive 24 while the other piston section 17 is provided with a complementary screw spindle 18 which engages the female part 16 of piston rod section 17. The end of piston rod section 17 opposite the screw spindle 18 is coupled with the connecting shaft 19 of the gear pair 20, 20 of a gear drive 2S. This gear drive 25 which is suitably constructed as a bevel-gear differential drive, com-prises a sun gear 21 driven at a constant speed by control motor 10.

When control motor 10 rotates at the same number of revolutions as the constant speed motor 22, the connecting shaft 19 of the gear drive 25 is at rest. If connecting shaft 19 does not rotate, piston 15 in turn is not actuated, and the valve open-ing of throttle valve 14 remains in the set position and allows a prescribed quantity of lubricant to pass to gapl 6. However, if the armature voltage of .control motor 10 is altered due to a variation in the height a of the lub-ricant gap 6, the speed of the control motor 10 varies with reference to that of the constant speed motor :22. This difference in the rotating speed between motors 10 and 22 causes the connecting shaft 19 of gear drive y to rotate in one or the other direction, depending on whether the control motor 10 rotates faster or slower Vthan the constant speed motor 22. The rotation of shaft -19 in one direction or the other direction causes piston rod section 17' to execute a corresponding rotation so that the threaded end 18 either screws into or out of the female part 16 of the two-part piston rod 17, 17 whereby the piston rod is respectively shortened or lengthened. The opening of valve 14 is in turn respectively enlarged or decreased and thus the amount of lubricant supplied to the pressure chambers 5 is controlled in response to the impulses derived from the sensing means 7 in the pressure chambers.

In the embodiment described above each of the sectorshaped pressure chambers 5 is supplied with lubricant from a pump 11 through a common v'feed pipe 12. -Each pressure chamber 5 has associated therewith a control device 23 as shown in FIG. 2. The construction and operation of the control devices 23 is conventional and does not form a part of this invention. These control devices are therefore not further described in the specification .nor illustrated in detail in the drawing. This arrangement has .the advantage that the face plate of a vertical lathe maintains always its prescribedrheight or its pred scribed distance from the support bed in a vertical direction.

Various modifications of the arrangement for regulating the height of the lubricating iilm on the slide tracks of machine tools will suggest themselves to persons skilled in the art, and it is understood that the embodiment described here represents only an illustration of the invention and is not intended as a limitation. Thus for example the throttle valve 14 could be actuated by magnetic means through the amplier 9. Furthermore the invention which has been illustrated in conjunction with the guide track of a vertical lathe can be applied, if necessary in a modified form, to machine tools having straight guide tracks.

What we claimas new and desire to secure by Letters Patent of the United States is:

l. An arrangement for regulating the height of the lubricating lm on the slide track of machine tools comprising in combination a face plate and a support bed, pressure chambers in said support bed along said slide track, pump means for feeding pressurized lubricating fluid to said pressure chambers an-d said slide track, valve means for proportioning said lubricating fluid to said pressure chambers, sensing means in said pressure chambers for measuring the height of said lubricating fluid on said slide track, reference means connected to said sensing means for comparing the desired height of said lubricating iiuid on said slide track to the actual height of said lubricating fluid on said slide track, and means connected to said reference means for actuating rsaid valve means in response to differences between the desired height and the actual height of said lubricating film.

2. An arrangement for regulating the height of the lubricating lilm on the slide track of machine tools comprising in combination a face plate and a support bed, pressure chambers in said support bed along said slide track, purnp means for feeding pressurized lubricating fluid to said pressure chambers and said slide track, valve means for proportioning said lubricating iiuid to said prepssure chambers, sensing means in said pressure chambers for measuring the height of said lubricating fluid on said slide track, reference means connected to said sensing means for comparing the desired height of said lubricating iluid on said slide track to the actual height of said lubricating fluid on said slide track, amplifying means connected to said reference means, a control motor connected to said amplifying means, gear means connected to said control motor and said valve means, said control motor actuating said gear means in response to differences between the desired height and the actual height of said lubricating iiuid to adjust said valve means and proportion said lubricating iiuid.

3. An arrangement for regulating the height of the lubricating film on the slide track of machine tools comprising in combination a face plate and a support bed, pressure chambers in said support bed along said slide track, pump means for feeding pressurized lubricating uid to said pressure chambers and said slide track, valve means for proportioning said lubricating fluid to said pressure chambers, sensing means in said pressure chambers for measuring the height of said lubricating uid on said slide track, reference means connected to said sensing means for comparing the desired height of said lubricating liuid on said slide track to the actual height of said lubricating liuid on said slide track, amplifying means connected to said reference means, a control motor connected to said amplifying means, a rst sun gear connected to said control motor, a bevel gear drive connected to said sun gear, a constant speed motor, a second sun gear connected to said bevel gear drive and said constant speed motor, shaft means interconnecting two opposite bevel gears of said bevel gear drive, a helically threaded spindle drive connected to said valve means and said shaft means, said control motor driving said iirst sun gear at a speed dissimilar to the speed of said second sun gear in response to differences between the desired height and the actual height of said lubricating uid to rotate said opposite bevel gears and said shaft, said rotation of said shaft operating said spindle drive to actuate said valve means and apportion said lubricating uid.

4. An arrangement for regulating the height of the lubricating film on the slide track of machine tools comprising in combination a face plate and a support bed, pressure chambers in said support bed along said slide track, pump means for feeding pressurized lubricating uid to said pressure chambers and said slide track, valve means for proportioning said lubricating iiuid to said pressure chambers, sensing means in said pressure chambers for measuring the height of said lubricating fluid on said slide track, reference means connected to said sensing means for comparing the desired height of said lubricating uid on sai-d slide track to the actual height of said lubricating fluid on said slide track, amplifying means connected to said reference means, a control motor connected to said amplifying means, a irst sun gear connected to said control motor, a bevel gear drive connected to said sun gear, a constant speed motor, a second sun gear connected to said bevel gear drive and said constant speed motor, shaft means interconnecting two opposite bevel gears of said bevel gear drive, a helically threaded spindle drive connected to said valve means and said shaft means, a two-part piston rod, an internally threaded portion at one end of one of said parts, an externally threaded portion at one end of the other of said parts, said externally threaded portion engaging said internally threaded portion, said two part piston rod connecting said valve means and said shaft means, both said motor means driving said first sun gear at a speed dissimilar to the speed of said second sun gear in response to differences between the desired height and the actual height of said lubricating fluid to rotate said bevel gears and said shaft means, said rotation of said shaft means moving said externally threaded portion within said internally threaded portion to vary the length of said twopart piston rod and actuate the valve means to proportion the lubricating uid.

References Cited in the le of this patent UNITED STATES PATENTS 502,557 Doolittle Aug. 1, 1893 1,154,785 Lemp Sept. 28, 1915 2,087,291 Moross July 20, 1937 2,782,602 Hamilton Feb. 26, 1957 2,788,862 Langer Apr. 16, 1957 2,939,289 Clark June 7, 1960 

